code: def test_bioul_tags_to_spans_without_labels(self):
      tag_sequence = ["B", "I", "L", "U", "U", "O"]
      spans = span_utils.bioul_tags_to_spans(tag_sequence)
      assert spans == [("", (0, 2)), ("", (3, 3)), ("", (4, 4))]
  
      tag_sequence = ["B", "I", "O"]
      with self.assertRaises(span_utils.InvalidTagSequence):
          spans = span_utils.bioul_tags_to_spans(tag_sequence)
  
file_path: magnitude/pymagnitude/third_party/allennlp/tests/data/dataset_readers/dataset_utils/span_utils_test.py
imports: from __future__ import with_statement
  from __future__ import absolute_import
  from allennlp.common.testing import AllenNlpTestCase
  from allennlp.data.dataset_readers.dataset_utils import span_utils
  from allennlp.data.tokenizers.word_tokenizer import SpacyWordSplitter
  from allennlp.data.tokenizers.token import Token
label_desc: Use image node_id 8 for calling the SpanUtilsTest obj's underlying member method code with example usage: obj.test_bioul_tags_to_spans_without_labels() without return types